This invention relates to a relay apparatus for relaying data and a relay method.
Explicit Congestion Notification (ECN), which is one of congestion notification technologies, is in the spotlight as an optional function installed in Linux (trademark), Windows (trademark), and other operating systems (OSes), and as a topic of active discussion at the Internet Engineering Task Force (IETF).
ECN is a congestion notification technology in which, when congestion occurs in a packet relaying apparatus that constitutes a part of a network, such as a router/switch, the router/switch itself explicitly marks a data packet transmitted from a transmitting terminal with congestion information, and transmits the marked data packet to a receiving terminal, thereby notifying the congestion information to the receiving terminal (see JP 2010-232876 A).
The congestion notification technology described above, however, is a technology of updating the Layer 3 (hereinafter abbreviated as L3) header field of a frame in L3 relay, and does not update the L3 header field in Layer 2 (hereinafter abbreviated as L2) relay. Congestion in a relay apparatus of an L2 network therefore cannot be notified with the above-mentioned technology. In addition, related-art relay apparatus do not execute an error check for the L3 header of a frame in L2 relay. Consequently, executing a rewrite of the L3 header in L2 relay in order to notify congestion corrects the L3 header erroneously. Data reliability may thus be impaired when a relay apparatus relays data packets of different layers.